Having done mostly customer facing positions for two decades:

The good news is, it’s not you. Customers are hell. Most assume you have all the resources in the world to help them and are choosing not to when you usually have only the most basic tools.

Hell, I’ve done jobs where the objective was to go to a location (think events, festivals) and hand out free (yes, gratis) food, drink, samples, and people will STILL complain, catch an attitude, and over-all act entitled.

I’m sorry you’re going through this. In my experience, it doesn’t get easier, but you get stronger, if that makes sense.